Historical ties to the word
Using the N word in any other situation other than an academic, literary setting, or other serious setting that does not put light to the word is wrong. There's no other way around, it should not be a source for laughs and it's not because humans no matter what country they are in are too sensitive.
It's because of the historical connotaion that it contains. It's tied to the worst period of American history. Using it lightly and comically almost shows utter disrespect for those who went through the horrible cruelty of slavery from which the word came forth. The N word is not simply just a word that has lost it's meaning in society over time. The historical connections that N word brings up are so recent and even if they weren't recent, are still of extreme importance to any person in the world, let alone America. So when someone decides to derive humor or relieve rage with the N word, they are saying that the absolutely disgusting act of slavery, cruelty, and white power are ok to put lightness to and to not take seriously.